15-31-312. Apportionment formula -- unitary business provisions. If the allocation and apportionment provisions of this part do not fairly represent the extent of the taxpayer's business activity in this state, the taxpayer may petition for or the tax administrator may require, in respect to all or any part of the taxpayer's business activity, if reasonable:
(1) separate accounting, provided the taxpayer's activities in this state are separate and distinct from its operations conducted outside this state and are not a part of a unitary business operation conducted within and without this state. For purposes of this part, a "unitary business" is one in which the business conducted within the state is dependent upon or contributory to the business conducted outside this state or if the units of the business within and without this state are closely allied and not capable of separate maintenance as independent businesses.
(2) the exclusions of any one or more of the factors;
(3) the inclusion of one or more additional factors which will fairly represent the taxpayer's business activity in this state; or
(4) the employment of any other method to effectuate an equitable allocation and apportionment of the taxpayer's income.